


like coins in the well

by favspacetwink



Category: Voltron: Legendary Defender
Genre: Galra Shiro (Voltron), Large Cock, M/M, Minor Allura/Lance (Voltron), Size Difference, Size Kink, Thirsty Keith
Language: English
Status: Completed
Published: 2019-07-08
Updated: 2019-07-08
Packaged: 2020-06-24 10:43:55
Rating: Explicit
Warnings: No Archive Warnings Apply
Chapters: 1
Words: 5,581
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/19722064
Author URL: https://archiveofourown.org/users/favspacetwink/pseuds/favspacetwink
Summary: Shiro outright laughs at that. “You’re cute.” Keith sputters in protest. “I’m not trying to be rude, I promise! I just – you don’t know what I did before I joined the Blades, do you?”“No,” says Keith. He tilts his head and peers up at Shiro. “I don’t know much about you at all, Shiro.”Shiro’s answering smile is almost… bashful, as is the way he scratches at the back of his neck. It’s an odd but endearing expression to see on a Galra. “Would you like to?”“What do you think?” Keith grins.





	like coins in the well

**Author's Note:**

> A full-length smutty Galra Shiro fic prompted by one of my twitter followers! Please enjoy!
> 
> I'm on twitter at [favspacetwink](http://twitter.com/favspacetwink) if you'd like to come scream about Voltron or, now, BNHA as well!

“I _know_ he has a huge dick. I just _know_ it.”

In the back of his mind, Keith is aware that breakfast might be a little bit too early to be having this conversation with Lance. In his defense, though, he’s been up all night thinking about this _,_ so there’s no way he wasn’t going to blurt it out to the first sympathetic person he saw this morning. Plus, Lance has a tendency to tell Keith about all his sexcapades with Allura completely unprompted, so Keith figures it’s only fair to burden him with this.

“You’re probably not wrong,” Lance says, pushing his food goo around in the bowl. “But – dude, what is he, like, eight-foot-five? Nine feet? If he’s, like, proportional, it’s not gonna fit. You’d hurt yourself.”

“It’ll fit,” Keith says confidently. “I’ll make it fit. I can do it.”

Lance makes a face that’s somewhere between impressed and revolted. “Gross, dude. Stick to taking normal-size dick like the rest of us.”

Across the table from them, Hunk and Pidge share a look.

“The rest of us aren’t taking _any-_ size dick,” Hunk points out. He pauses. “Wait, Allura has a dick?” Another pause. “Wait, that was – that’s none of my business, I’m sorry–”

“She has whatever she feels like having,” Lance says with a smug grin. “She’s a shapeshifter.”

Pidge and Hunk’s eyes widen.

“Wait, how did you guys not know that?” Keith asks. “Why am I the only one he’s been constantly oversharing with?”

“Solidarity, man,” Lance says, like that’s a fucking answer. “You’re the only person I’ve met who’s a bigger bottom than I am. You _get_ me.”

He has a point, but it’s a stupid one. “Doesn’t mean I don’t judge the hell out of you.”

Lance grins. “Right back atcha, Galra cocksleeve.”

Keith screeches and launches himself at Lance. They spend the next minute and a half tussling on the floor as Pidge and Hunk calmly eat their breakfast.

“Hey, Keith, when you guys are done, I have a question,” Pidge says.

Keith secures Lance in a headlock and grunts, victorious. “What is it?”

“Are you talking about this because this guy – what’s his name again–”

“Shiro.”

“-because Shiro, um, propositioned you or something? Or are you just super thirsty?”

“He’s just thirsty,” Lance mumbles, partially muffled by Keith’s arm.

Keith laughs and lets him go. “No one’s propositioned anyone yet, Pidge.”

Pidge hums and nods.

 _“But,”_ Keith says, getting back into his seat, “that will hopefully change next time we work with the Blades.”

“Here we go,” Lance says, still on the floor.

Hunk gulps. “I have a bad feeling about this.”

xx

Keith may be thirsty, but contrary to what the rest of his team sometimes likes to pretend, he’s not stupid. He knows the Blade of Marmora as an organization is an important ally to Team Voltron and that offending one of their members with unwanted advances would not be a smart move, strategically.

However.

From the handful of times Keith’s interacted with Shiro – the large, scarred, purple-furred Galra who’s been plaguing his thoughts for the past few weeks – he’s fairly sure his advances wouldn’t be unwanted.

Shiro looks intimidating, sure; he’s big, even for a Galra. But in reality, he’s actually pretty shy. He had honest-to-god _blushed_ when Keith complimented him on his fighting techniques during their last visit to the Blades’ secret base. Keith had sparred with a few of the Blades when they had downtime, interested in learning how his Galra lineage shaped his fighting style.

Shiro was the only one Keith couldn’t beat hand-to-hand. He’d pinned Keith to the mat, their faces so close that Keith could see the faint lilac scar over the bridge of his nose, and the two of them had ended up grinning breathlessly at each other for several long, long seconds before Shiro’s cheeks colored and he offered Keith a hand up.

Keith remembers how overwhelming it had been to be pinned beneath him, the absolute _rush_ he got from looking up at such a powerful creature and knowing he was completely at his mercy, if only for a few precious seconds. He had tried to act casual about it, to compliment Shiro without making it obvious how turned on he was, but Lance once told him that full-blooded Galra could “smell if you’re horny,” so Keith isn’t sure if he succeeded.

 _Fuck,_ he needs to get laid.

The point is, Keith hadn’t even known Galra _could_ blush until he made Shiro do it twice in one day, and he’s sure he’s not imagining how Shiro had lingered a little longer than necessary on top of him before standing up and helping Keith do the same.

It should probably be embarrassing how little effort it’s taken the large Galra to completely consume Keith’s thoughts. After all, a few lingering moments aren’t _that_ much to go on – Keith is definitely going to need more proof than that before he makes a move and risks offending their allies.

xx

Keith wants proof, and he gets all that and more the next time they visit the Blade of Marmora headquarters to discuss strategy.

The organization’s stoic leader, of all people, ends up giving Keith the perfect opportunity to spend time alone with his ill-advised crush.

“…and those files are archived somewhere in our library,” Kolivan is saying, words flowing over Keith like soothing music designed to put him straight to sleep. That is, until- “Shiro, you’re the one most familiar with its organization. Why don’t you take one of the paladins with you to search?”

“Of course, sir.”

Shiro’s rich, deep voice has the opposite effect of Kolivan’s – Keith is instantly awake, sitting up straight in his chair and gazing expectantly at Shiro as the rest of the paladins pointedly keep their eyes down.

Keith, meanwhile, locks gazes with Shiro and smiles at him. Shiro doesn’t blush, but it seems like he comes close, the corner of his mouth twitching as he blinks a few times.

“Keith?”

“Yeah, let’s go,” Keith says, trying not to sound too eager.

From the way Lance snorts into his sleeve, he absolutely fails in that respect.

The library is _huge._ It feels so much larger from the inside than the amount of hallway space it takes up from the outside that Keith has to wonder if some kind of advanced, space-bending technology is being used to maintain it. It almost feels like magic when they step inside.

_“Whoa.”_

“Pretty impressive, right?” Shiro grins.

“I – yeah,” Keith breathes. “How are you supposed to find anything, though?”

The shelves look like they stretch on for miles, every inch filled with books and papers instead of the digital files Keith was expecting. Keith feels like he could get lost and starve in here and it would take everyone else _days_ to find his body. Talk about knowledge or death.

“Lucky you’re with me,” Shiro says, still grinning. “Part of our training includes organization and management of the archives.”

“Ugh,” Keith groans. “Am I gonna have to do that if I decide to go through the trials? Wait – is staying awake during library training one of the trials?”

Shiro bursts into laughter and Keith feels his chest puff up, pleased he could make the Galra laugh like that as they wander deeper into the stacks. “No, the training comes after the trials. Are you really thinking of joining the Blades? I thought you had to – y’know, lead Voltron.”

Keith hums. “I do have to, but I am. Thinking about it, I mean.” Shiro snorts softly. “Haven’t figured out how that’s gonna work yet.”

“You’ll do well,” Shiro tells him. “Especially if I decide to get mysteriously ill on the day of your trials.”

It takes Keith a moment to realize that Shiro is _teasing_ him. He gasps. “I could take you.”

Shiro outright _laughs_ at that. “You’re cute.” Keith sputters in protest. “I’m not trying to be rude, I promise! I just – you don’t know what I did before I joined the Blades, do you?”

“No,” says Keith. He tilts his head and peers up at Shiro. “I don’t know much about you at all, Shiro.”

Shiro’s answering smile is almost… bashful, as is the way he scratches at the back of his neck. It’s an odd but endearing expression to see on a Galra. “Would you like to?”

“What do you think?” Keith grins. He sucks in a breath for courage and deliberately knocks his side into Shiro’s as they continue through the stacks.

xx

An hour later finds the two of them side by side at a small table in one corner of the library, several file folders deep into the research Kolivan had requested. Keith’s pressed so close to Shiro that their sides are touching, fueled by a desire to be close to him after how much time they just spent talking about Shiro’s past.

Keith never would have guessed that the gentle Galra spent over a year as a prisoner on one of Zarkon’s ships fighting in the gladiator pits for others’ entertainment. Shiro had been able to talk freely and openly about it, no hesitance in his voice as he recalled his experiences, but it had broken Keith’s heart all the same.

Shiro had been captured while on a mission with the Blades. It had taken over a year before one of the Blades’ undercover operatives was able to arrange for his escape without blowing their cover or compromising their own mission. Shiro had taken this in stride, explaining to Keith that the safety and goals of the Blade of Marmora came before his own, but Keith isn’t so sure he’d be able to immediately return to working for the same organization that basically abandoned him in prison for a year.

Scratch that, he _knows_ he wouldn’t be able to ever work for an organization like that again. His definition of loyalty has always been more personal. Keith can’t imagine how forgiving Shiro must be to continue going on dangerous missions for the Blades after what he’s been through.

After about half an hour of discussion, the two of them had finally remembered the reason they were in the library in the first place and had quickly settled back into their assigned task. Something has changed between them, though, Keith can feel it.

He feels it in the casual way Shiro reclines next to him, allowing Keith into his space as his ears stay relaxed and content.

Five minutes later, as Keith’s mind starts to wander away from the text he’s pretending to read and his eyelids start to droop, a thought occurs to him. “Hey, sparring doesn’t, like, bring up bad memories for you, does it?”

Shiro huffs out a quiet laugh. “I’ll admit that after I was rescued the last thing I wanted to do was ever fight again, but my loyalty is still pledged to the Blade of Marmora, Keith. Part of my job description includes physically fighting against hostiles.”

“Yeah, but – what you went through…”

“I know. I – it wasn’t great, at first. It was actually more difficult to fight my peers than to fight my enemies, because I was used to holding nothing back.”

Keith sucks in a breath and looks over at Shiro. The library is warm and Keith is sleepy, giving the atmosphere of their conversation a surreal, fuzzy quality to it.

“But I readjusted over time,” Shiro continues. “It’s… touching, that you’re concerned.”

Keith swallows. “Anyone would be.”

Shiro laughs. “Not just anyone. You’re special, Keith. No one else on your team has taken the time to really get to know any of us-”

“Yeah, but – it’s ‘cause they’re not Galra-”

“No, it’s because you’re _you,”_ Shiro says warmly.

If Keith thought this conversation was surreal before, it’s nothing compared to the way the room feels now, like every molecule of oxygen’s gotten twice as heavy. A slow smile creeps onto Keith’s face.

“D’you wanna take a break and grab some food?”

Shiro sighs. “Kolivan will be disappointed if I come back empty-handed. I think I only need about another half-varga to find what we’re looking for, though.”

Keith groans and rests his head on the table, eyes sore from skimming through small-printed texts for a few specific characters Shiro has copied neatly on a datapad for Keith’s reference. “Shirooo.”

“You can take a nap, Keith,” Shiro chuckles. “I don’t mind. It’s nice to have the company, even if you’re asleep.”

“Mmkay,” Keith murmurs, pillowing his arms underneath his head to make himself more comfortable. “Sorry m’not helping.”

Shiro makes a noise that Keith’s sleepy brain can’t interpret. “You are.”

An indeterminate amount of time later, Keith feels a gentle hand in his hair. He must have fallen asleep, or at least drifted to that place in between consciousness and unconsciousness.

“Keith. Hey, Keith. I’m all done.”

There’s Shiro’s voice. Deep and hushed, laced with mirth. Keith hopes he wasn’t drooling or anything like that; he hums happily when Shiro’s large fingers slide through his hair, then sucks in a quiet breath when Shiro’s thumb brushes over his cheek.

“Keeeith. I know you’re awake,” Shiro teases.

Keith _is_ awake – now very much so, thanks to the close proximity of Shiro’s fingers to his mouth. His stomach twists as he tries to figure out what he should do next, how bold he can be without messing things up.

He settles on turning his head ever-so-slightly and pressing his mouth against Shiro’s thumb in a lazy imitation of a kiss.

Shiro sucks in a startled breath; his hand twitches, but he doesn’t move his thumb away. Keith’s stomach rolls in anticipation and he purses his lips against Shiro’s skin to make it abundantly clear that the contact wasn’t an accident.

“Keith,” he hears Shiro breathe.

His fingers tremble against Keith’s scalp. Keith keeps his eyes carefully closed, gathers his courage, and darts his tongue out to lick the tip of Shiro’s thumb.

Shiro _gasps._

Keith’s heart is slamming fast against his ribs as he runs his tongue over his own lips to wet them before parting them further and sucking the tip of Shiro’s thumb into his mouth. A low growl rumbles from Shiro’s throat, making the fine hairs on the back of Keith’s neck stand up, and it’s not a warning growl telling Keith to stop – far from it. Keith keeps going, suckling a little harder to show Shiro just what he wants to do to other parts of his body.

“Keith – oh,” Shiro whispers.

His hand trembles, and Keith can practically taste how much he’s restraining himself. He wishes Shiro wasn’t – he wants that control to snap, and it’s just a matter of time before Keith figures out how to make that happen.

“You said I was special,” he murmurs, releasing Shiro’s thumb with a wet _pop_ before he speaks. Shiro groans. “Did you mean it?”

“Yes,” Shiro says immediately. “But I wasn’t – wasn’t just trying to flatter you, you know.”

Keith tentatively opens his eyes and gasps at the way Shiro is looking at him. “I know.”

They stare at each other for a few seconds, so intensely heated that Keith imagines anything straying into the path of their locked gazes would immediately combust. Then Shiro’s eyes drop to his lips and he rubs his large thumb, still wet with spit, over the corner of Keith’s mouth.

That’s it.

Keith gathers his courage and surges up to close the distance between their mouths, nearly rising out of his seat to get to Shiro even though the Galra is still sitting down. Their lips meet with a wet sound, plush and tentative, and Keith is sure he can’t be the only one who feels the spark of energy that jumps between them.

Shiro sucks in a breath through his nose and grabs onto Keith’s upper arm, grip too tight for just a fraction of a second before he seems to remember himself and relaxes. He groans low in his throat when Keith sucks on his bottom lip, worrying it with his blunt fangs until Shiro licks at the seam of his mouth. He’s insistent about it, growing less tentative with each passing second, and Keith moans outright when he opens his mouth for Shiro’s probing tongue and discovers that it’s the size of a small human dick.

 _Fuck._ Just how big is Shiro’s _actual_ dick, then?

Still half-standing, Keith squirms, fighting against his instincts telling him to crawl into Shiro’s lap as their tongues slide together. Shiro makes that noise in his throat again and lets go of Keith’s arms to cup his face in surprisingly gentle hands.

Keith’s face flames when a whimper tears out of him unbidden.

He tries to press closer, standing up a little more into his awkward half-squat to make the angle better between their mouths, and reaches up to grip onto Shiro’s biceps for stability. The muscles are huge – Keith’s hand doesn’t even span the width of his arm.

“Keith,” Shiro breathes, sliding a hand over his cheek.

He reaches down with the other, grips Keith’s flank, then picks him up like he weighs nothing before depositing Keith on his lap so they can continue kissing. Keith moans outright and wiggles in his lap, hoping Shiro’s hand will continue to wander, but Shiro rests it on the small of his back instead.

Keith isn’t sure how much time they spend like that. This isn’t his first kiss by any means, but it’s the first kiss he’s had that doesn’t feel like a battle, or a competition. Shiro is gentle but insistent, not trying to prove anything – just trying to make Keith feel good.

It’s completely overwhelming.

Sitting in Shiro’s lap, Keith still has to crane his neck up to kiss him. Every part of Shiro’s body is a constant reminder of how much larger he is than Keith, and as Keith starts to get hard in his paladin uniform he feels an increasing pressure underneath him and wonders, is that – is that–

He grinds down and pulls the most delicious noise from deep in Shiro’s chest.

Oh, fuck.

“Keith.” Shiro breaks the kiss to take a deep breath. “What do you – how much–” He takes another breath to collect himself; Keith has never seen him so flustered. “What can I give you?”

Keith grins and grinds down against Shiro’s massive cock once more. “I have a few ideas.”

A deep purple blush spreads across Shiro’s cheeks, teeth sinking into his bottom lip. Fuck, Keith wants Shiro to bite him with those sharp fangs, mark him up all over.

“I just meant – I don’t want to do more than you’re comfortable with.”

That’s cute. Luckily for Shiro, Keith is comfortable with anything.

“And I don’t want to hurt you,” Shiro adds.

Keith hisses out a breath. “You won’t.”

Shiro still looks hesitant – conflicted about hurting Keith with his larger size, apparently – so Keith drags his head down to kiss him again, surprising himself with how content he is to just do this for the time being.

After everything he’s learned about Shiro today, Keith’s priority is no longer taking his dick just to see if he can – it’s to make Shiro feel good. His heart feels too big for his chest.

Then Shiro’s communicator chirps, interrupting their moment. Shiro grunts and fumbles it out of his pocket, unlocking the screen while he glares at it.

“It’s Kolivan.”

Keith snorts and lays his head on Shiro’s chest. “Is he wondering what’s taking us so long?”

“Pretty much,” says Shiro.

Even though they’re no longer kissing, Shiro hasn’t removed his hand from Keith’s back, even as he uses the other one to type something into his communicator. Ear against his chest, Keith can hear the Galra’s heartbeat; it’s as fast as his own.

“Shiro.”

“Mmm?”

“There isn’t any chance you can, uh, give this intel to Kolivan electronically instead of in person, right?”

Shiro sighs. “Even if I encrypted it, it’s safer to deliver in person.” He shifts Keith on his lap and their erections push against each other, making both of them gasp. “Although I understand why you’re asking that.”

Keith giggles. “I figured. It’s probably for the best, anyway, ‘cause I don’t have lube on me and I’m guessing you don’t either.”

“I – oh. No.” If possible, Shiro’s face colors even deeper. “I have some in my quarters.”

“Mmm,” Keith hums. He cranes his neck to kiss up the line of Shiro’s jaw, smiling when Shiro’s claws dig ever-so-slightly into the small of his back. “Maybe you should show me the way there before you go to see Kolivan.”

Shiro shudders.

xx

Once Shiro has left Keith on his bed and gone to deliver physical copies of the files to Kolivan’s office, Keith takes a few big, deep breaths. Okay. This is happening. This is really happening.

Time to get to work.

Part of him worries that Shiro will have fully lost the mood by the time he returns from whatever lecture Kolivan is bound to give him, but Keith can’t let that stop him from getting ready. It’s going to take a _lot_ of preparation to fit Shiro’s monster cock inside him, and he needs all the head start he can get.

He’s still half-hard from making out with Shiro in the library, but he avoids touching his dick as he strips his clothes off and uncaps the bottle of lube. Keith can already tell it’s going to be a struggle to last once Shiro is back with him, so there’s no sense in making it even more difficult for himself by jerking off now.

Keith lays on his back, head turned to the side and buried in Shiro’s pillow as he takes in the delicious scent that’s clinging to the pillowcase, the sheets, Shiro’s entire _room._ He breathes in deep and moans, the concentrated scent overwhelming as he spreads his legs and starts to tease around the rim of his hole with one lubed-up finger.

He doesn’t have long to wait; only a few minutes later, he hears the door to Shiro’s quarters open, and Shiro appears in the bedroom within seconds.

His jaw drops when he sees Keith.

“That was fast,” Keith purrs, now two fingers deep and scissoring gently.

“K-Keith,” Shiro stammers. “I – I…”

The uncertainty in his voice makes Keith pause, praying he hadn’t misread the situation. “Yeah?”

Shiro’s eyes are fixed between his legs. Keith blushes but doesn’t remove his fingers. “When you asked about lube, I… I assumed that meant _you_ wanted to fuck _me.”_

“But I do want to fuck you,” Keith says, confused. Then, _“Oh._ You mean-”

“I didn’t think it was going to, uh, be possible the other way around,” Shiro says, scratching the back of his neck. He’s blushing to the tips of his furry purple ears.

Keith narrows his eyes. “It will.” He pauses. “Unless you don’t… want to? That way?”

“No, I… I do. That’s how I usually prefer to.” Keith lets out a sigh of relief. “But Keith… you’re a lot smaller than I am. I don’t know if this is going to work.”

“Then you better come over here and help me get ready,” Keith grins. “Because I’m going to make it work.”

Shiro’s eyes finally wander back up to Keith’s face as he makes his way over to the bed and crawls on top of Keith, stroking the side of his face tenderly. “I don’t want to hurt you.”

That’s the second time he’s said that; Keith has to reassure him, for the second time, “You won’t, Shiro.”

The trust and connection he feels with the Galra is unlike anything that’s gripped him before. Keith needs to find a way to convey that with his body.

He tugs at Shiro’s black uniform with his clean hand, helps him strip the layers off as Shiro tries to divide his attention between getting naked and exploring between Keith’s legs. This was poor planning on Keith’s part; he barely has the mental energy to appreciate the expanse of purple skin that’s being revealed to him once Shiro’s clever fingers start stroking over his hole.

Shiro traces over the rim, feels where Keith still has two fingers crooked inside himself, and Keith keens when he applies just the barest amount of pressure.

Shiro’s so much taller than him that he ends up looming over him like this, his pecs at Keith’s eye level when Keith strains to reach down and help free the waistband of Shiro’s uniform. There’s a smattering of darker fur over his chest, the same color as the hair on his head – a deep purple, almost black.

He’s so handsome. Keith melts a little more into the bed and whimpers when the man above him hisses and presses a thick, _thick_ finger into his hole alongside two of Keith’s own.

“That’s it, sweetheart, relax for me,” Shiro murmurs.

Forget melting – Keith feels sunshine burst inside him and he’s surprised he doesn’t liquefy and run off the bed. _Sweetheart._ He pushes his hips up against Shiro’s hand and hides his face in Shiro’s massive chest.

He becomes useless quickly. Shiro’s fingers aren’t just large, they’re _knowing,_ too; Shiro adds another finger and wastes no time finding Keith’s prostate, crooking his fingers against the sensitive spot over and over until Keith’s dick is drooling all over his stomach and his fingers sit motionless inside himself.

“Oh, that’s good,” Shiro groans. He eases Keith’s fingers out so he can fit another of his own inside and really start fucking Keith with them, punching little whines from his lips. “You take it so well.”

Proud satisfaction lights up in Keith’s chest even in his dazed state. “T-told you.”

Shiro chuckles. “You did. Gods, you’re beautiful.”

His three fingers combined are the girth of the largest toy that Keith owns, so it’s only once Shiro adds a _fourth_ finger that the stretch finally starts to burn, temporary discomfort prickling in and around Keith’s hole.

_“Nnnh…”_

“Yeah, sweetheart, I know it’s a lot,” Shiro whispers. “D’you want me to stop?”

Keith grabs his arm. “Don’t you – ungh – don’t you _dare.”_

Shiro makes a hungry sound and bends himself nearly in half so he can kiss Keith, his tongue lewdly imitating the motion of his fingers as he slowly works Keith open, spreads him apart. Keith grabs blindly for Shiro’s cock, starting to feel frantic, and moans loud and long when he finds it and discovers his hand doesn’t even come close to wrapping around it.

The angle is off and he doesn’t have much space between their bodies but Keith gives Shiro a few strokes all the same, smoothing precome up and down the length of his cock. Shiro’s fingers stutter inside him; he makes a soft noise in his throat that Keith takes a few seconds to recognize as a _purr._

“Shiro,” he says, delighted.

“I can’t help it,” Shiro grits out between deep, satisfied purrs.

He spreads his fingers out and Keith moans at the stretch, the burn fading as his prostate gets attention again. “Fuck – oh, _fuck,_ please–”

“I think you’re ready,” Shiro murmurs. “Gods, Keith, you’re amazing.”

Keith feels smug. “And you didn’t th-think I could do it.”

“Mmm, how wrong I was.” Shiro pulls his fingers out with a loud _shlick_ that has Keith whining at the sudden emptiness. His grip tightens on Shiro’s cock, possessive. “How do you want to do this?”

Keith has had a lot – _a lot –_ of time to think about this exact situation. He knows what he wants and what will be the most comfortable for him.

Shiro honest-to-god _growls_ when Keith rolls onto his belly and pushes his ass up. “Look at you.”

Keith twists his neck to look, and his breath catches in his chest at the sheer power radiating off the Galra behind him. Shiro pushes his uniform leggings the rest of the way down then meets Keith’s eyes, his own pupils dark pools of lust as he grips Keith’s hips and rests his cock on the small of Keith’s back.

“F-fuck,” Keith stammers out, fighting the urge to shove against him.

The rest of Shiro’s eyes are practically glowing in the dim lighting; this is the most feral Keith’s ever seen him, and he can’t help but shiver as he watches Shiro dump a generous glob of lube into his hand and smear it messily all over his cock and the outside of Keith’s hole. Just watching it makes Keith’s cock twitch, so he quickly turns back and buries his face in Shiro’s pillow, breathing in his scent and suddenly feeling so, so empty.

“Ready, Keith?” Shiro asks.

Keith grips the pillow with both hands and nods. “Want it, c’mon.”

He feels one large hand spread his cheeks apart, then jolts when the huge tip of Shiro’s cock rubs over his hole. Keith wants to push back onto it but something stops him, probably because he knows Shiro’s the one who can actually see what he’s doing.

When Keith feels the stretch intensify as Shiro starts to push inside, he moans into the pillow, shaking as he tries to stay still. Oh shit – oh, _shit,_ he’s big, bigger than anything Keith’s ever taken before, stretching him to his absolute limits. It hurts as Shiro pushes inside – Keith moves a hand down to his cock to keep himself hard – but his body is managing to accommodate it, wrapped tightly around his monster of a dick.

Shiro pauses and rubs over Keith’s back, letting go of his ass now that he’s inside. “Are you okay?”

“Mhmm,” Keith mumbles, face burning to discover that he’s already wetting the pillow with drool _and_ tears. “Is it in?”

“I, um. About half of it.” Keith gasps. _Only half_ feels like _this?_ “Do you want to keep going?”

“Yes,” Keith pleads.

By the time he feels Shiro’s hips press against his ass, Keith is panting, half-out of his mind as his fist flies over his cock. The line between pain and pleasure has completely blurred, obliterated now that Shiro’s carved out a space inside him; he doesn’t know which way is up, which way he should move, what any of the sensations he’s experiencing actually mean-

“Stars above,” Shiro breathes. He digs his claws into Keith’s hips. “You’re _so_ tight – are you sure you’re okay?”

“I said I’m fine,” Keith insists. He needs Shiro to _move;_ he can’t take another second of this overwhelming stretch. “Just – do it, c’mon, fuck me–”

Shiro pulls back and pushes inside. It’s a gentle movement, all things considered – but the sliding pressure against his prostate and the deep, _deep_ fullness absolutely shatter Keith and he screams into the pillow, cock _dripping_ and balls tight from just one thrust.

“Keith-”

“Don’t fucking st-stop,” he moans, white-knuckling the pillow. “F-fuck-”

Shiro does it again and Keith’s eyes cross. Again, and his legs start to tremble. It feels like – but no way, it’s way too soon–

Another thrust. “Ahhngh–”

“Take it, just like that,” Shiro grunts, claws digging even deeper. Again. “Good boy.”

Heat surges in Keith’s belly and he bites the pillow as one more agonizing thrust of the huge cock inside him sends him over the edge and into the most unexpected, intense orgasm of his entire life. His body tries to clench around Shiro’s cock but he’s impaled so wide around its thick length that all his muscles do is flutter weakly even as his hole squeezes hard, his legs giving out as Shiro holds up his hips. Keith’s out of his mind, no shame as he screams into the pillow and drips come all over Shiro’s sheets.

Behind him, Shiro swears loudly and pulls out a few inches. Keith whines and tries to press back, but Shiro’s firm grip on him stops him.

Once his muscles work, Keith glances back and realizes that Shiro pulled out so that he wouldn’t pop his knot inside Keith’s ass when he came. _Fuck._ Keith knew most male Galra had knots, but he had completely forgotten about it in the heat of the moment. He’s not sure he would’ve survived being split open on that thing.

Maybe that’s a new goal he can work toward, though…

“Keith, oh gods,” Shiro breathes. “That was – you really liked it that much?”

Keith’s face flames and he turns to bury it back in the pillow. “I’m sorry,” he mumbles. “I couldn’t help it.”

Shiro laughs, bumping his knot up against Keith’s ass. Keith clenches with a little aftershock and both of them moan. “Don’t apologize, sweetheart.”

“Yeah, but we barely lasted a minute,” Keith says. 

“Mmm, are you saying we have to practice more?” Shiro hums, leaning down so he can kiss the back of Keith’s neck while staying buried inside him. Keith gasps and squirms, pinned down. “Fuck until your little hole can take this big dick for hours? I bet we can work up to that.”

Keith is _shocked_ to hear Shiro talk like that; another aftershock races through him, a drop of come dribbling out onto the already-ruined sheets. “Oh my god…”

“Is that a yes?”

Keith smirks and tilts his neck so the Galra has more access to kiss him. “I think we’re going to need to do a lot more research together in the library. Lots of private meetings, too.”

Shiro chuckles and scrapes his fangs against Keith’s throat. “I think you’re right.”

**Author's Note:**

> I hope you enjoyed! Leave a comment to let me know what you thought!


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